Radio-electric receiver, particularly for watch on broad frequency bands



'Ndv. 30,1948.

Filed May 24, 1943 62 RA 010 DIRECT/0N F/NOER RADIO-ELECTRIC RECEIVER, PARTICULARLY FOR WATCH on BROAD FREQUENCY BANDS 4' Sheets-Sheet 2 Mam/P 5 4 o/sm/az/rox osc/LuraR /1011 1, IF/ER QJc/LLATM 77 8.455 clRCu/r INVENTOR REA/ HA RD y M M ATTORNEY I Patented Nov. 30, 1948 2,454,797 IO-ELECTRIC RECEIVER, PARTICU- snor BANDS Rene My, Lyon, France,

' Z Y FOR WATCH ON BROAD FRE- 1 nor to Enternational Standard Electric Corporation, New York, N. Y a corporation of Delaware piication May 2%, 1943, Serial No. 488,294

in France May 17, Mei

Section 1, Public Law 690, August 8, i948 tent exp May 1'1, 196i 25 Claims. i

This invention relates to radloelectri'c receiving systems, and a particular object thereof is to provide a radio direction finding system which simultaneously provides supervision of the'transmissions in progress in a certain range of irequenoies.

Another object of the invention is to provide a radio directionflnding receiver system in which there is a considerable reduction over known systems in the time devoted to the search for stations, which are desired to be detected by radio.

Another object of the invention is to provide a radio direction finding receiver system which insures continuous supervision of the transmissions taking place in a definite frequency range and which permits individualmonitoring of each of the transmissions in progress without interrupting the supervision of the transmissions and without interfering with the direction'finding operations. Another object of the invention is to provide improved indicators for radio direction finding receiver systems of this kind that permit the obtaining of various combinations of the indications required in these systems without superfluous indications or ambiguity.

Another object of the invention is to provide a radio direction finding receiver system insuring supervision of the transmissions in progress in a definite range of frequencies and permitting individual monitoring of transmissions in progress which will make possible the transportation and remote repetition of the indications obtained 0211137.

According to certain features of the invention, a radio direction finding receiver system comprises a receiver that is provided with means for modifying its tuning continuously or automatically in a predetermined range of frequencies, and indicating instruments such as a cathode ray oscilograph connected to the said receiver by means of circuits causing the appearance on its screen of simultaneous traces of all the radio transmissions in progress within the supervised range, a

directional wave collector system of orientable reception pattern feeding the receiver in order to,

permit successive cancellation of the various traces of the transmissions that appear on the indicating instrument, and means for obtaining a visual indication of direction each time that the trace of a transmission peers on the indicating instrument.

is blotted out or disap According to another feature of the invention, means are provided, in a radio direction finding receiver of this kind having continuous supervision of the transmission, for avoiding the appearance of a double series of indications that would result from the fact that the elements that modify the tuning of the receiver produce two successive scannings of the reciever that are asymmetrical in frequency for one single complete scanning of the indicating instrument.

According to another feature of the invention, means are provided in a radio direction finding receiver of this kind for producing the appearance of the indications of direction on the screen of the indicating instrument that is used for the supervision of the transmissions in progress.

According to another feature of the invention, means are provided in a transmission supervising radio direction finding receiver of this kind for changing, as desired, from an automatic supervision of the transmission to a manual search and to the monitoring of the various transmissions, and, in this case, for employing as regulating frequency indicator the same indicating instrument as for the supervision of the transmissions in progress.

According to another feature of the invention, arrangements are made in the above-mentioned receiver systems for use of an additional receiver for the monitoring of the transmission, the same indicating instrument being used to obtain, on a single scale of frequencies, the simultaneous directlonal indications of the transmissions in mmress and of the manual adjustment of the monitoring receiver.

According, to another feature of the invention, an additional monitoring receiver is employed and means are provided for using the same indicating instrument for obtaining simultaneously the indications of the frequencies of the supervised transmissions and of the monitored transmissions and the indications of the directions of the transmissions located by radio.

According to another feature of the invention,

an additional monitoring receiver is employed and the radio direction finding circuit may or may not be changed over from the control receiver to the monitoring receiver.

i assays? A radio direction finding receiver system which incorporates features of the invention comprises a directional wave colleetorassembly which feeds a receiver that has its tuning modified continuously, e. g. by rotation of the variable tuning condenser, and the output of the receiver is apmodification of the characteristics of the aerial collectors, e. g. by rotation of these serials or by rotation of a finder associated with stationary directional aerlals. Each time that the directional system passes over a position of zero reception of a transmission, the luminous trace that corresponds to this transmission disappears on the screen of the oscillograph. The direction of this transmission is then read on a dial associated with the collector assembly.

In a system ofv this kind, it is evident that the luminous traces that indicate the positions in frequency of the various transmissions are more or less clearly marked according to the position of angular keying of the directional aerials. If it is desired to cause the disappearance of such irregularities duringthe intervals between the radio direction finding measurements it is possible, "according to one feature of the invention, to make use of a non-directional aerial to which the receiver is connected during these intervals,

the input of the receiver being switched, e. g. by means of a key, to the directional serials when it is desired to take a bearing.

According to one feature of the invention, the use of a single indicating instrument for the simultaneous supervision of transmissions in progress and for successively locating these trans. missions is made possible by adding to the radio direction finding circuit a scanning system simi: lar to the one used for causing the appearance of the control indications. These two scanning circuits are synchronized with each other and are switched to a cadence that is sumciently rapid to insure the persistence of the two series of luminous indications on the screen of the cathode ray oscillograph.

In order to be able to switch from supervision of the transmissions on the frequency band oi the receiver to the manual locating of these tra r" sions, one feature of the invention provides for the use of a device for the manual control of the receivers tuning condenser in association with a coupling system that enables this manual control to be hooked in at the same time as the disconnecting of the continuous drive motor or the opening of the excitation circuit of this motor. This manual control device may be provided with a special indicating dial but, according to one feature of the invention, it is preferably disposed so as to control the scanning of the indieating cathode ray tube in such a. way as to cause the appearance of a luminous trace corresponding to its angular position, thus acting as a luminous index of the frequency adjustment of the receiver. This index may be switched with the indication of direction in the manner described above.

During the frequency scanning of the receiver by its tuning element, whether this scanning is done by rotation or oscillation of the said tuning element, the same positions will be found twice in the explored range of frequeneies'for one complete song of the indicating instrument. It is not possible to use a double speed scanning of the indicating instrument because the identical positions in the frequency range are not reproduced at symmetrical locations in time with respectto the moment when the scanning of the indicator begins. Two different series of indications will thus be produced on the screen of this indicator. It is consequently suitable to suppress one of these series of indications in order to avoid any risk of error. In the particular case in which the scanning of the indicator is arranged to be circular, it is sumcient to mask one half of the screen. As a rule however, the invention provides for the use of means for extinguishing the luminous image which appears on the screen of the cathode ray oscillograph during the half of the scanning that corresponds to the superfluous seriesof indications.

According to certain features of the invention, these meanseonsist of electrostatic commutators having two elements or structures coupled capacitively and rotating with respect to each other, the shapes given to these elements or structures being such that the capacitive coupling varies during their rotation'from a value which permits the transmission of an alternating voltage from one element or structure to the other to a value which prevents any transmission of alternating voltage. The rotation or the relative displacement of the two elements or structures is synchronized to the scanning of the indicating instrument in such; way that the transmitted voltage may serve for blocking the cathode beam during desired periods of the seaming.

In order to permit simultaneous monitoring of the operations of supervision and direction finding, an auxiliary receiver is added to the control receiver in the above systems. This receiver may have a non-directional aerial, for example, and may be arranged so as to cover the same band width as the control and radio direction finding receiver. In this case, in order to make it easier to adjust the said monitoring receiver to the frequency of a detected transmission and consequently to increase the rapidity of this adjust.

ment, another feature of the invention provides means for causing the appearance of a luminous index superposed on the luminous traces that reveal the presence of transmissions in progress, this luminous index indicating'the adjustment position of the tuning elements of the monitoring receiver. These means consist of a scanning circuit whose action is commutated with that of the similar scanning circuit controlled by the control receiver. The cadence of the commutation of the two scanning circuits is sufiiciently rapid to insure the persistence of the supervision and adjustment indications of the monitoring receiver on the screen of the cathode ray oscillograph. In order to monitor one of the transmissions detected by the control receiver, it will then sumce, by adjustment of the manual tuning element of the monitoring receiver, to bring the luminous index indicating its position on to the luminous trace of the wanted transmission.

The cadence of commutation of the two scannings may suitably be that which is furnished by the periodical blocking of the control reeeivers scanning circuit in order to avoid the appearance of two aeriesof indications on the screen of the cathode ray tube. The electrostatic commutator or other means used for this purpose is then mod- 5 ideal in order to set in operation the monitoring receiver's scanning circuit during the periods when the control scanning circuit is blocked instead of simply omitting all scanning of the oscillograph during these periods.

When two separate receivers with only one indicator, are used ior supervision and monitoring, the radio direction bearings may be obtained as mentioned above by modifying the directional pattern of the control receiver's aerials in order successively to eilace the luminous traces that correspond to the transmissions in progress, and by reading the directions thus obtained on a separate dial. By another method, non-directional aerials may be provided for the two receivers, and one of these aerials may be switched to aradio direction-finding commutator system that is set in operation at the moments when bearings are to be taken.

However, according to certain of its features the invention likewise provides for also producing the appearance of the direction indications on the same cathode ray tube screen as the indications of the frequencies of the supervised and monitored transmissions. Use may be made for this purpose of a third scanning circuit oi the same speed as the two others and controlled by the angular position of the radio direction -finding ages proceeding from the control receiver circuit,

the monitoring receiver circuit and the radio direction finding circuit that is associated with one of these receivers. Three different simultaneous indications then appear on the screen oi the indicator.

According to still other features of the invention, the difierent indication currents are used to modulate a current or a carrier wave, and this current or this modulated wave is then remote transmitted to one or more indicators similar to the locally employed indicator in order to effect remote transportation and repetition of the ob tained angular indication.

These objects and features, as well as. others,

. will be explained in detail in the following description given with reference to the appended drawings, in which: Fig. 1 illustrates schematically one example of an embodiment of a radio direction finding receiver that effects simultaneous supervision of transmissions in progress;

Fig. 2 shows schematically one example of a as means for suppressing on the said screen the traces that would be obtained during the superfluous portion of the frequency scannin Figs. 4A and 43 respectively. show how the indicating tube screen looks when the operation is manual and when it is automatic;

Fig. 5 illustrates schematically another embodiment or a radio direction finder with supervision of transmissions in progress which comprises means for causing the appearance of the various desired indications on a single screen of an indicating instrument;

Fig. 6 illustrates schematically one example of an electrostatic commutator that can be used for periodically supplying a blocking voltage to a cathode ray indicator;

' Figs. 7, 8 and 9 illustrate schematically, as examples, various applications of an electrostatic commutator of this kind;

Figs. 10 and 11 are schematic views of two E nqodiflcations of the electrostatic commutator of Fig. 12 illustrates schematically one embodiment of a radio direction finding receiver that efiects simultaneous supervision of transmissions in progress and the monitoring of one particular a for the various desired indications;

resistance-coupled distributor that can be used in the circuit of Fig. 1;

Fig. 3 is a schematic view of one example of a radio direction finding receiver effecting simultaneous supervision of transmissions in progress that is provided with means for causing the appearance on the indicating cathode ray tube screen either of traces of the transmissions in progress in the case of automatically controlled operation, or of a trace that corresponds to the angular position of the receivers tuning condenser in the case of manual adjustment, as well Fig. 13 is a view of a cathode ray tube screen with the supervision and monitoring indications obtained with the circuit'of Fig. 12

Fig. 14. illustrates schematically another example of an embodiment of aradio direction finding receiver which, with a single indicating instrument, efiectssupervision of transmissions in progress, monitoring of a particular station, and taking of the bearings of the supervised transmissions;

Figs. 15v and 15A show diagrams used in the explanation of the operation of the arrangement of Fig. 14;

Fig. 16 is a view showing the use of the cathode ray tube screen as an indicator of the embodiment of Fig. 14, and

Fig. 17 illustrates schematically one example of a radio direction finding receiver system of one of the types described in connection with the preceding figures that is specially adapted for a easily repeating the obtained indications to a distance.

Fig. 1 gives a schematic view of one embodi ment of a direction finding and transmission system which employs features of the invention.

The dial i, or the indicating needle 2, is mechan- 'ically connected to an assembly of variable condensers 3, 5 and 5, for example. These variable condensers 3, i and 5 are electrically connected to high frequency circuits 6, i and 8 which serve as input circuitsto the detecting amplifier 9. As a whole they accordingly form a scanning condenser. The first high frequency circuit 6 may be connected by means of a changeover switch it either to a vertical antenna or other nondirectlonal aerial ill or to a radio direction finder circuit H, which may comprise any system of rotary commutators or crossed or directional antenna arrangements which permit the taking of radio direction bearings. The variable condensers, such as 5, d and 5, may be operated manually as a whole, as in an ordinary radio receiver, so as to search fora station. However a driving system by means of a motor l3 can make them rotate continuously, e. g. at the rate of 25 or 50 revolutions per second, and the assembly of variable condensers will accordingly eifect a completescanning of the reception range covered'by the receiver for-each revolution of motor i3.

Each time that the frequency exploring or scanning condensers 3, 4, pass'over an adjustment thatcorresponds to the reception of a station, a rapid variation of the output current of receiver 9 will occur during the brief time of passage over this wavelength. It is then possible to;use an indicator such as a cathode ray tube It? that is suitably fed bythe circuit of receiver 9 in such a way that each received station will correspond to a luminous trace that will permit indication of its presence and knowledge of its frequency. Receiver 9 may be connected to the cathode ray tube. ie by any suitable circuit and particularly by a. resistance-coupled distributor i6 driven in rotation by the motor It.

This kind of distributor is well known in radio direction finding and a schematic example of it is shown in Fig. 2. The output tube l6 of the detector-amplifier 9 and the high voltage W for the receiver feed at diametral points a resistance'coupled commutator it that consists of a chain of resistances all connected to circular contact studs. When the output tube It is not modulated, the supply current of the resistancecoupled commutator is constant and the distribution of the values of the resistances is such that when the assembly rotates there is obtained at the stationary brush terminals ii and la a sinusoidal voltage which consists of values of very close successive voltages. This sinusoidal voltage is applied to a pair of deflection plates, e. g. IQ, of cathode ray tube It, while sinusoidal voltage tapped at the terminals of the stationary brushes 20 and 2! is applied to the other pair of plates 22 of the cathode ray indicator It. When the current of the output tube is constant, the luminous spot of the indicating tube describes a circle on the fluorescent screen as a result of the two sinusoidal voltages in quadrature produced by the rotary commutator it. Now if the plate current of the output tube It is modulated, the more the grid is negative, the less the voltage will be on the commutator 15, and the diameter of the circle will be all the smaller. A high frequency modulation, e. g. pulses acting on the grid of the output tube l6, will be reproduced in the form of radial deflections on the screen of the cathode ray tube it. If, for example, at a given moment the variable condenser assembly 3, 6, 5 passes in rotation through a frequency at which the receiver receives the signals of a station, a rapid modulation of the output tube l6 will give the pip 23 on the screen of tube Hi; and by a rapid modulation of the tube, as the condenser assembly tunes through the frequency band, a secondstatlon will produce the pip 24. This occurrence is repeated upon each rotation of the scanning condensers driven by motor I3.

occasionthe flnder's angular position that-causes the disappearance of the trace of a station on the cathode ray tube screen inorder immediately to know the direction of this station.

Furthermore, an audible indication may be given by an earphone'or a loudspeaker, such as 25, connected to the output of the detecting amplifier 9.

. A modification oi the system of Fig. 1 is shown in Fig. 3. According to certain features of the invention, the circuitof this Fig. 3 is arranged in such a way that it is possible to cause the simultaneous appearance on the screen of the indicating cathode ray tube it of the stations that are operating, in case the variable condensers 8. d are driven mechanically in a uniform rotating motion by motor 13, or the position of adJustment of the variable condenser, which is usually read by means of a needle that moves in front of a dial, in case manual adjustment is used for receiver.

In the embodiment shown in Fig. 3, the indicating cathode ray tube It is shown in the If the input of the circuit 8 is connected to the radio direction finder ii, it is evident that when the finder is adjusted manually or in any other way to an annular position such that the transmission that corresponds to the pip 23 lies in the zero reception plane of the finder, this pip will become extinguished on-the screen of the cathode ray tube. Consequently, by manual adjustment of the radio direction finder II, it will be possible to cause the successive disappearance of any one of the indications of stations that appear on the screen of cathode ray tube It, It will be sumcient to read on each form of an oscillograph in which the deflection of the beam is effected by a magnetic circuit 28 that rotates around the tube. This magnetic circuit 26 is driven by motor It with a continuous and sufficiently rapid motion for the luminous spot that appears on the screen of the cathode ray tube to have the form of a regular circle. The variable condenser 3-4, which is double in the example shown in this figure, is driven by the motor is and controls the tuning of the high frequency circuits 6 and 'i which, together with the detector-amplifier 9, form a part of the receiver. The antenna to or any other radio direction finding device is arranged at the input of this receiver. The output circuit of detector-amplifier 9 controls the deflection of the spot by means of the magnetic circuit or winding which is connected to the output of detector-amplifier ii through the brush 27. If the output circuit of receiver 8-'i9 does not receive any modulation resulting from the passage of the tuning condenser through the frequency of a station, the path described by the spot is indeed a uniform circle, but the variations of voltage produced by the reception of a transmission correspond to radial deflections of the spot which produce the images 28, 29 and 30, shown in Fig. 4B, for example. These images represent transmitting stations that are operating at different frequencies. They may be directed toward the outside of the screen or toward the center according to the way the modulation is arranged.

The variable condenser 3-4 may be actuated manually by an adjusting knob 3| which occupics the uncoupling position 32 when the motor I3 is in rotation. The motor is set in operation,

e. g. by the stop 33 which controls the closing of relay 34. The coupling disc 35 of the manual drive system is then in position 36. When it is desired to adjust the receiver manually, the driving disc 35 applies against a disc 31 that is integral with shaft 38 of the variable condenser 3-4. When the knob 3| sets the condenser assembly in rotation, it also drives coil 26 which is integral with shaft 38. The spot then occupies on the graduated scale 39 of the screen of cathode ray tube iii a position that depends on the adjustment'of the condensers. By manual adjustment it is then possible to observe the exact location of a station, not only from the fact that the station can be heard if a loudacuyer speaker is connected to the output cirouit, but

In theories of the manual adiustment it is also possible to have coil 2tied by an alternating voltage so as merely to cause the appearance on the cathode ray tube screen of a radial line to (Fig. in) that serves as index or pointer for the regulating dial. To do this it is sufl'lcient to arrange for a switching of the power supply oi 001126. 7 V

When the condenser rotates, .it successively scans for a displacement of 180' the entire range of frequencies of the receiver, and, unless the condensers are made of special desi r the same stations will be found twice for each rotation, but the distribution 01 the stations is not the em eror these two half turns. It is therefore advisable to cut out the feed of the cathoderay tube during the undesired half turn in order to eliminate the corresponding luminous indications on its screen.

' For this purpose, use is made of a commutator or quire only a low-coupling capacity with the dei'cctor circuit M. This coupling capacity is lurnished by two electrodes es and M disposed in such a way that the high'irequency voltage can only pass from one electrode to the other during a half turn of the variable condenser t-t. As shown in Fig. 3, this can be done byusing an armature so attached to the condenser shalt 3i! and arranged to rotate in betweenplates it and it; this may consist of a circular scent oi such a shape that it is only capacitively coupled to the two plates case over 180 oi its circumferonce. The detector circuit or. during the portion of the rotation in which it is coupled to oscillator d l, detects a high frequency voltage that proceeds from oscillator M. It consequently applies a suitable direct voltage to the control grid so oi the indicating tube It which extinguisher; the spot each time that the high frequency proceeding from oscillator ii arrives in detector 62,1. e. during a half turn per complete rotation, with the above arrangement. Various'other examples of designs and uses of such commutators will be described further on in this specification.

Fig. 5 shows a modification oi the circuit 01' 'Fig. 1 in order to be ableto obtain simultaneously the indication of stations that are operating and the indication of the angular position of the radio direction finder on a single cathode ray tube. The wave collectors or direction finding circuits GI and 62 are connected to the receiver 86 by means of the finder 63. The tuning circuits of this receiver are controlled by the variable condensers es and 68 which may be driven, either manually by the knob or and the coupling 68 or continuously by the motor is. Cathode ray tube Ill. whose magnetic deflection circuits H are connected to amplifier 12, serves io'r giving simultaneous indications of angles and of frequencies of the received stations. Amplifier '52 may be connected to the receiver equipment by a line 13 of any required length. A commutator 76 permits the alternating connection or the cathode ray tubes deflation circuits 1 i to the distribution lines lb or it by means of amplifier i2 and line 13; these distribution lines being respectively connected to circuits El and t2. Circuit-ll may conslot of a rotating potentiomctric distributor, similsr to that shown in Fig. 2, or oi an induction ied via line it by distributor 82 which is similar to circuit, such as a radio direction finder with reversed connections. This circuit ll has its rotor ted by the carrier current amplifier 78 modulated by receiver as. x N The cathode ray tube that is connected by line it to the brushes oi the stators of circuit ll is accordingly controlled in such a way that the luminous spot will describe a circle onits screen and occupy an angular radial position that corresponds to the angular position oi the rotor of circuit ii. If the condenser rotates continuously, the rotor of circuit i! will rotate at the same time, since it is on the same shaft, and the spot will describe a circle or on the screen as of cathode ray tube it.

Ii the receiverpasses through a transmission station for a position corresponding to the fre- .quency of this station, there will appear on screen so the luminous trace so that reveals the presence ,0! this station. This phenomenon appears continuously if the rotation of the mechanical assem-= bly t5, 6d, ii is efiected at suficient speed, i, e. oi the order of 60 revolutions per second.

When the contact of commutator is is connected to the distributor circuit it, amplifier i2 is rotorof distributor 32, i. e. the angular position or the rotor of radio direction finder 8t that is controlled by the manual knob M.

When commutator Hi is connected to the distributor circuit at, it is easy to superpose by means of this circuit on the constant deflection current an alternating current that radially fmodulates the spot of the cathode ray tube in such a way as to transform point 88 into a radial line 89. This line 89 represents the angle made by the rotor of the radio direction finder 63 with respect to a predetermined fixed guide mark 81.

Circuits it, t0 and dlserve for extinguishing the semi-circumierence 92 described by the spot for the undesired angular positions of the variable condensers t5 and 68. The circuit may be an oscillator similar to that described in connection with Fig. 3, circuit 19 a detector, and 8! the commutator for interrupting the oscillations during the unwanted half of the tuning cycle.

Advantage may also be taken of the periods during which the variable condensers 65 and 66 cannot be used for indication of the stations in course of operation in order to produce the trace d9 of the angle of the rotor with respect to a fixed guide mark. It is evident that the mechanical commutator it may be replaced by an electronic commutator in the known manner.

19, 8t and ill illustrate an assembly similar to that described in connection with Fig. 3 for supassays? 11 pressing the illum ination of the cathode ray tube durng the undesired periods of the condensers rot tion. However, generator 80, instead of controlling the extinction of the cathode ray tube, may be used for controlling the operation of distributor 02 in order to alternate the indications of frequency and of direction of the received stations.

The manual control 61, which may be used for adjustment of the receiver by means of the coupling 80, can also serve for causing the appearance ofan angular indication in a manner similar to that described in connection with P1 .3.

%)n the screen 86 of the cathode ray tube I there are accordingly obtained a certain number of traces 85 that indicate the position in the frequency spectrum of the transmitting radio stations actually operating in a definite wave range covered by the receiver. There is obtained at the same time an indication 09 which has the shape of a luminous radial line that corresponds to the angular position of the radio direction finder and makes it possible to determine successively the direction of each of these stations.

In the case of manual adjustment of the re- 6 comprises a stationary sector I02 which may be of any shape and which is connected to a terminal I 00. A voltage of highvalue is applied between terminal I03 and shaft I00 of the commu-' tator which rotates in synchronism with the other rotating elements of a circuit similar to those shown in Figs. 3 and 5. This shaft I00 carries, for example, a small sector IOI which is capacitively connected to the stationary sector I02 during a portion of the rotation. A high frequency voltage is transmitted from terminal I03 static interrupter of Fig. 6 is shown in Fig. 7. In

be produced that makes it possible to know the frequency to which the receiver is adjusted. The mechanical or electronic commutator 14 may in this case be set in oscillation in any suitable manner for rapidly alternating the indications of the angular positions of the finder 60 and of the variable condenser 65-80.

In all the cases in which a circular scanning is employed, it is of course possible to arrange a simple shutter on the undesired portion of the screen in order to avoid seeing the superfluous indications. However, as already indicated, it is preferable to provide means for blocking the scanning during the undesired periods in order to be able to use them for other purposes, e. g. for different indications.

Figs. 3 and 5 illustrate schematically a type of an electrostati commutator that makes it possible to cut off the illumination of the cathode ray tube during one half of each scanning rotation by acting on the control grid of the cathode ray tube or on any other electrode that controls the illumination of the screen.

Itis not always possible to employ grid controlled tubes in cathode ray indicators for receivers used for supervision or other purposes. There are, for example, cathode ray tubes in which the luminous intensity is controlled by the adjustment of an auxiliary plate voltage. Besides, it may be desirable to avoid modulating the control grid of a cathode ray tube.

The modulation that permits extinction of the undesired indications may consequently be applied to an auxiliary anode of the tube in the form of an additional voltage that is suppressed or considerably reduced during the undesired periods. It is also possible, by modifying the value of the anode voltage, to increase the radius of the circle during a half-tum in order to bring it out ofa visible region of the screen.

Various examples of elecrostatic commutators and of their applications for suppressing undesired indications on a cathode ray tube screen will now be described with reference to Figs. 6 to 11 inclusive. These designs and circuits may consequently be used instead of the corresponding designs and circuits of Figs. 3 and 5.

The electrostatic commutator illustrated in F18.

this Fig. 7, the high or mean frequency transformer I06 transfers the amplified current of the receiverto the diode detector circuit IIO. When sector II! of the electrostatic commutator is in front of the stationary electrode I01, the high frequency current will be detected at the terminals of resistance I00 and by means of the connection I08 it may be applied to any modulation or other amplifying system'that can cause the appearance on the cathode ray tube's fluorescent screen of the indication of the traces of the received stations. During the portion of the undesired rotation of the rotating plate condenser. sector II1 is idle and the modulation does not act further on' the cathode ray tube.

According to one modification of the circuit as shown in Fig. 8, the mean frequency transformer III feeds the detection diode I I2. Resistance I I3, at the terminals of which the detected current appears, controls the potential of the grid of amplifier tube IIO which is suitably biased by potentiometer Ill. A coupling transformer IIII whose secondary winding is connected in the control grid circuit of tube'IIO and whose primary winding is connected to a source II 5' of high frequency oscillations makes it possible for tube II8 to act as a modulator tube, so as to obtain in the output transformer IIO a high frequency voltage modulated by the detected signal. The output circuit of transformer H0 is connected to the vertical deflect-ion plates III and I22 of a cathode ray tube whose horizontal plates I23 and I26 are, for example, fed by a scanning voltage that proceeds from a linear time base circuit I25.

When there is no modulation, the deflection of the spot on the cathode ray tube's screen is confined to a line I 20 and use can be made of the electrostatic commutator 0, controlled by shaft I02 in synchronism with the receiver's rotating plate condenser or with any other element that forms part of the assembly driven by the motor or by the manually controlled knob, to cause the production of the vertical modulation during a definite time interval only. The traces of stations I21 and I28 can appear during this period. The amplitudes and the shapes of current desired at the terminals of plates I2I and I2: may be obtained by means of connected-in networks of impedances arranged in any well known manner according to requirements.

This Fig. 8 and the following one show a cathode ray tube used with a linear scanning, but it must be understood that the invention is of course not limited to the use of the circular scanning em loyed in'the other examples of embodiments sh wn and described, but, on the contrary, may beadapted to any desired known method of scanning. I

In anotheryariant of the circuit of Fig. 7, which is shown in Fig. 9, the mean frequency transformer I 28 symmetrically applies the output current of the receiver to the vertical deflection plates Itl and I82'of cathoderay osclllograph I8jii. This vertical modulation, e. g. as shown at I31, I88, of the horizontal trace of the scanning I36 that is produced by plates I33 and I84 to which the linear time base circuit I33 is connected. is eii'ected when the movable sector of rotating commutator I88 permits the passage of the alternating voltages. 7

It must be understood that the electrostatic commutator discussed above may be used in all cases in which it is desirable in general to permit the passage of a high or mean frequency voltage, or simply an alternating voltage, from one circuit to another during a portion of the rotation of an assembly, and to prevent the pass-age of these alternating currents when it is desired to avoid their effects in the second circuit.

A commutator of this kind may be of any suitable design, e. g. of designs like those shown in Figs. 10 and 11. In Fig. 10 the rotating shaft I39 is made integral with an insulating member M8 that has a metallic coating, a secondary shaft M3 being carried by this insulating member Mil Instead of using a single receiver that alternatively permits supervision of the transmisvision of the transmissions inprogress, adjust- I in order to be driven in rotation by shaft I without metallic connection between them; Secondary shaft I88 carries condenser blades or segments IM, I which rotate between segments M6, I ll, IE8 that are stationary and are con-- uted according to the profiles of the stationary and movable sectors of the condenser segments I'M to M8 are accordingly tapped at I48. Inversely. the high frequency voltage may be applied to'terminal M9 and be tapped at terminal hi2. A connection arrangement of this kind permits insulation of the electrostatic commutator with respect to earth. If however this precaution is not advisable, shafts I43 and I89 may be of one piece and terminal I42 may be con nected to earth, for example.

The design shown in Fig. 11 comprises an insulating cylinder I5! driven by a shaft I58. This cylinder I M has its outer surface metallized in the manner indicated at I52 and I53. for example. A metallic ring I54 surrounds the metallized portion I53 and is spacedtherefrom, while sectors, such as I51 and I58, are capacitively joined to the metallized portion I52. A grounded electrostatic screen I59 separates the two assemblies of electrodes. With this arrangement, it is only during a portion of the rotation of drum I 5i that electrode I54 can transmit the alternating voltages applied to it by terminal 155 to electrodes I 51 and I58, accordingly to terminals I80 and I56, respectively.

It is evident that electrostatic commutators as described above may be used in other circuits than those of the kind shown in Figs. 3 and 5 for periodically blocking the cathode beam of an indicating oscillograph. They can be used in a general way for periodically transmitting alter- I sions in progress in a predetermined range and individual monitoring of the various transmissions thus located. it may be preferable in certain cases to use two receivers in order to be able to continue the supervision of the operating transmitting stations while monitoring one of them and while radio direction finding indications are obtained as desired, as in the case of the'preceding systems. In this case, certain featuresof the invention also provide means for only using one single indicating instrument for super ment of the monitoring receiver, and the indications 'ofdirections. Figs. 12 to 17 show various examples of embodiments of these two-receiver systems.

In the example of embodiment illustrated in Fig. 12, a control receiver I81 and a monitoring receiver I IB are shown associated in such a way as to use only one single indicating instrument. such as a cathode ray oscillograph WI.

The tuning circuit of control receiver .lt'l, e. g. a rotating plate condenser I89, is driven in continuous rotation by means of amotor I88 in such a way as successively to tune receiver it? through all the frequencies of the range covered by condenser its, e. g. ata speed of the order of revolutions per second, or of any other suitable value for producing a circular pattern I63 on screen I82 of the cathode ray tube IGI. The stations operating within the supervised frequency range appear on this pattern I83 in the form of radial traces I88 directed outward or inward according to the direction selected for the variation of the voltage that produces them and distorts the circular scanning. The thus modulated circular scanning is produced, for example, by an induction rotating system ltd, such as an electromagnetic deflection coil driven in rotation around the neck of cathode ray tube Iti by the same motor I68 that drives the tuning circuit I89 of control receiver I'8'l in the manner indicated by the connection I16, or at least in synchronism with this tuning circuit. This coil I is fed by the output of receiver I61, e. g. by means of a wiper collector ring I66.

Since tuning condenser I69 has only one useful rotation, the portion of its rotation from 180 to 360 that reproduces the frequency exploration obtained in its rotation from 0 to ,180 but asymmetrically with respect to this first explora-' tlon, it is necessary to suppress on the screen of the indicating oscillograph IBI the luminous traces that correspond to this undesired portion of the exploration. As mentioned above, the operation of receiver I6! is blocked during the undesired halfturn of variable condenser I69. can be eiiected by means of an oscillator Ill and a commutator IIIl that is also driven in synchronism with condenser I89, so as to apply to receiver I67 a blocking voltage proceeding from oscillator III during the undesired periods of the rotation of condenser I89.

In this way. each time that the tuning circuit of receiver I61 comes across a transmission during the exploration of the frequency range covered by this receiver, there will appear on screen I62 a, radial trace that makes visible the presence of the transmitting station. It is of course advisable to choose extreme selectivity for the re ceiver I61, so that the stations may appear on screen I62 of the indicating tube IGI in the 0 of .well separated radial trace I88.

This

I assays? The monitoring receiver I18 is of similar design to control receiver I81, but its tuning circuit, e. g. a rotating plate condenser I11, has an angular position that is manually adjustable by means of a knob I18. In order to effect easy and rapid ad,'.ustment of this monitoring receiver to the frequency of any of the transmitting stations located by the radial traces I88.on screen I82, the rotor of a reversed radio direction finder of goniometer I18 is keyed to the shaft of rotation of the manually adjustable condenser I11. This rotor is fed by a suitable high frequency source which, in the example shown in the drawing, consists of the oscillator I1I already used for suppressing the undesired indications on screen I82 oi the indicator. This high frequency voltage may be directly applied to the rotor of the reversed finder I18 from commutator I18, so that the voltage transmitted to rotor I18 Is periodically interrupted at the cadence of interruption of the feed of coil I88 but during supplementary periods.

The high frequency voltage applied to the rotor of the reversed tinder I18 is transmitted to the two stators, and the two voltages in quadrature thus obtained are applied by the detecting amplifier circuit I12 to a circular scanning circuit I18 arranged for radial deflectionof the spot. This deflection circuit may be of any well known electrostatic or electromagnetic type. This willresult in the appearance on screen I82 of oscillosraph I5I of a, radial line I88 whose angular position will depend on the angular position of the rotor with respect to the stators of the reversed finder I18, accordingly on the angular position of tuning condenser I11 under control of the manual knob I18. I

The rotation of motor I88, accordingly the operating time of commutator I18, is to be selected sufficiently rapid, e. g. 50 cycles per second as mentioned above, for the alternation of the two scannings' produced by circuits I88 and I18 to take place at a cadence that will insure persistence of the luminous indications due to these two scannings. Accordingly, on screen I12 there will actually be obtained the simultaneous indications of the stations detected by the control receiver I81 and of the adjustment position of monitoring receiver I18.

Since the tuning condensers I88 and l'l'l'of recelvers I 81 and I18 are disposed so as to cover the same frequency range during their rotation, and since the two scannings are controlled at the same speed, it results that when the luminous spot actuated by the circular scanning system I88 is at a definite frequency, it will positively occupy the same angular position as when it is deflected Receiver I18 may be connected to a monitoring device I18, e. g. a loudspeaker or an earphone, and/ or to any other indicating or servicing device, either for the recording or retransmission of signals or for radio direction finding purposes, by connecting the input circuits of receiver I18 to suitable aerial systems. Besides, the outputs of for remote angle rpetition, e. g. to a circuit ter-g mlnating in one or more cathode ray indicators similar to that of Fig. l, in order directly to reproduce the angular indications substantially without IneztLa and with all desirable fidelity.

In systems of this kind, it is of course possible to modify the luminosity of the various portions of the obtained images by displacement of the spot. Thus in Fig. 13. which illustrates the screen I82 of a cathode ray tube employed as indicator in the manner just described, the'radial traces I82, I88 and I88 of the stations in course of operation may appear strongly luminous, as well as the luminous pointer I88 for adjustment of the monitoring receiver. On the other hand, the circular scanning pattern I82 that moves along the graduated scale I8I and gives the scale of the frequencies is of attenuated luminosity. Since such methods for varying the luminosity of indications 48 diameter.

on a cathode ray tube screen by variations of bias are well known per se, they will not be explained in detail.

Fig. 14, to which reference is now made, shows schematically one embodiment which permits the observation of transmitting stations in course of operation over a wide frequency range, the adiustment of a monitoring receiver to a particular transmission, and the taking of the radiodirectional bearing of this transmission manually or by automatic direct reading. In this embodiment. certain features of the invention provide for the use of only one single circular scanning system for producing-the various desired indications on a, cathode ray tube screen.

This method is specially suitable when use is I made of cathode ray tubes that have a large screen Only magnetic deflection is employed with this kind of tube, and, in viewof the dimensions and the considerable voltages that are used, it is advisable to concentrate the deflection field as much as possible, since this permits construction of tubes that are of small diameter in the cylindrical portion. In order to employ only one single deflection system, the receiving circuit shown in Fig. 14 provides for a magnetic circuit 282 which rotates around the neck of cathode ray tube 28I. The rotation of this circuit 282 permits circular displacement oi the spot on screen 2" of the cathode ray tube 28I. This deflection system 282 is connected by commutator 283 to the output stages 2I8 of the control receivers 2I2 and the monitoring receiver 238. A commutation, e. g. electronic, is provided in order to permit alternate connection of the supply circuit of the circular deflection element 282 either to the control receiver 2I2 or to the amplifier-circuit 2I8 which is fed in such a way as to furnish the position of the frequency adjustment of monitoring receiver 288. Motor 284 drives in continuous rotary motion the assembly of the devices secured to shaft 288, i. e. the deflection system 282, the rotating tuning condenser 288 of control receiver 2I2, the high frequency static distributor such as 281 that feeds the commutation device 2 I I of the out- .put stages 2I3. and the induction distributor or finder-288 whose orthogonal stators 28I and 282 occupy a definite fixed angular position.

As described above, instead of efiecting the seaming of cathode ray tube 28I by means of a variable condenser of special profile, the scanning is performed by. a tuning condenser of the control receiver 2 I: that is of normal shape our ins: only 180 01 its rotation. The second helt= his the undesired half-turn of variable condenser let, clistri butor tt'l gives the output circuit lit oi receiver 2E2 such a bias that receiver iii! no longer acts on the circular scanning of magnetic element 2M, and this causes the spot to appear on the cathode ray tube screen only during one half-turn 236.

On the same shait es the variable tuning con- 'denser 2273 of the monitoring receiver there is keyed an induction distributor 22% whose two orthogonal stators .229 end its occupy fixcci pcsi tions. Variable condenser 32? may, for exnmple, he controlled manually by the adjusting lmoh 22% and this condenser is given sprofile similar to that of the rotating variable condenser tilt, so as to use the same scale of frequencies on screen 2 ii for the indication of the adjustment oi monitoring receiver 233 as'ior the indications of supervision. induction distributor 223 comprises e rotor which has its angular position controlled by knob 2th and which cietermines the phsse re lotions or the sinusoidal voltages induced in the orthogonal stators 22s and 2st. The rotor of distributor 228 receives over the constant coupling transformer 23 2' s high frequency voltage. proceeding, for example, from the oscillator tit s1- ready used for the commutation of the output circuits. The high frequency voltage induced in the stators 229 and 28B is transmitted to two other stators 23a and it? within which the rotor oi? induction distributor. 2% rotates, which ciistributor, 'by means of the constant couplinstmnsformer 253s, restores'to output amplifier lit the high frequency-voltage proceeding from the first induction distributor. The angular position lot which the induced voltage will he nil in the rotor of distributor 2% will of course depend on the angular position of the rotor oi. induction rlis= tributor 22s.

In Fig. 15, curve 252 shows the variation in ampiituci-euuring the progressive rotation of shaft 205 of the high frequency current that enters amplifier till. This voltage variation is used hi means of output circuit lit for operating this circuit during the half-turn when the cathode ray tube flili does not serve for giving the control 4 indication. The directly amplified high treuuem cy voltage might be used ever known t mes of circuits, but it is preferable to detect the envelope curve 2 32 in order to use the continuous ecrn-= In Fig. A, the circle 2% illustrates the circular path described by the spot on u cathode ray tube whose'rotsting deflection circuit is-fecl by the continuous component, and the image miiillustrstes the trajectory of the spot when the circular deflection system 202 is fed by i e curve of the type of component 2% that actuctes an output tube whose cut-oil point P only permits empiificstion of the voltage tip 2% during the time t.t Xtds this tip this that furnishes the image 2%, This image would be double, i. e. there wouicl'iae two similar images staggered by 180 if cathode ray tube till was used during the complete rotation of the circular scanning for giving an indication oi the component detected by amplifier BIB. But since the tube is only used.

assesses;

during a heli.-turn, as mentioned above. only the single image 2% will appear; Thei'shsps oi this image will depend on the saturation point oi the output tube, onthe chsrscteristies oi the de tection, on the polarizations, and on the site of the signal. It is usual to obtain very tuner-eel images in which the single a is very small, which corresponds to e very short time t- The image it: may then be almost confused with e. ruulul.

line.

On screen it?! of cathocle the variable condenser 2271 that tunes the, 211 3111 toring receiver 235; Since the same frequency scale is used, it is ecsy to bring the luminous the control grid of the cathode ray tube to ram force the luminous traces etc, tilt), Ziii (Flu. it) that represent stations detectedhy the control receiver iiil'encl to diminish to at great extent the luminosity of the reference semi-whole In order to cvoicl any confusion with the imsss sss oi the index that shows the adjustment in frequency 01 the monitoring receiver to the other images prorluceu on cathode ray tube it up peers preferable to have the image of this luminous index EVQZBEM as e. dotted line. accomplished during the appearance of this icicles; by modulating the grid. of the cathode ray lav moons of s high frequency signal that permits successive illumination and extinction, or simply very rapid modulcticn in intensity, of the spot of the cathode rev 'tuce during the relatively slow recital rlisplccement that furnishes the image 252.

The monitoring receiver 213$ may he'ennnecterl to on electronic or mechanical commute-tor tilt that permits-monitoring or trsiilc ever a 219i! telling the receiver to'sn cute-line system see of the hinrl usually employed in radio direction ins, it beins nossible to take the bearing menus-1 iv in; the control knob lei or by on automatic finding device. It is then possible to key on the some shaft on induction distributor lit: of a. kind usually usetl for the remote transmission of the rsdio-clireeticuel or other indicsticns in order to repeat to a distance the angular indications of the radio direction finder.

By s combination similar to that just described for causing the indication of the adjustment ire== quency of the receiver to opp-ear on cathode rev tuhe Eti simultaneously with the control indies ticnthe image of the direction of the monitored stetion may he produced on this some tube by siterneting this indication with the others but st is cadence that is suillcien't for retaining luminous persistence of all the indications. This image mes be the one that corresponds to the manual adjustment of control knob E li, 'Tcut it men also be the one produced automatically icy the transmitter producing the signal tilt to which rev mussel oi it there is consequently obtained the luminous. my 2213 which indicates the sngulsr nositicn of This is the monitoring receiver is adjusted, as shown by ably of different radii.- so as not to overcrowd the 4 same scale.

The radiodirectional image 283 may be obtained by keying on the rotary shaft 205 a resistance l coupled distributor having a sinusoidal distribution of the voltages. By means of the commuta- "tion circuit 01. the output stages 2N, direct use may also be made in the circular scanning circuit 202 of the output voltage of receiver 238 which may itself be fed by a rotating radio direction finder, either manually or at a constant speed in synchronism with the rotation of the scanning circuit 202.

In the various embodiments that have Just been described, the cathode ray tube that is used as indicator is located directly in the axis of rotation of the frequency scanning system. According to certain of its features, the invention also provides circuit arrangements that permit the indicating cathode ray tube to be located at a certain distance from the axis of the mechanical scanning system while retaining the synchronous circular deflection, and while using a single deflection system. An arrangement'of this kind also makes it possible to use several indicating sys-.

tems that may without particular difficulty rc-"' peat the indications to considerable distances.

In Fig. 17, which illustrates schematically one I example of an arrangement of this kind, the cathode ray tube 23! comprises a rectangular dcfiectionsystem 282. This deflection system may consist of pairs of orthogonal plates, or stationary inductanc'es. Deflection system 282 is connected to an amplifier or'detector 2G3 which is itself connected. to a carrier current generator 288 by lines 265 and 28B and across a rotating induc tion distributor 251. The carrier current is mod- -ulated by the different'signals that it is desired to show on the screen of the indicating cathode ray tube till. This assembiy constitutes the remote repetition circuit thatpermits the connection to line 2% of a certain number of amplifying elements in association with indicating cathoderay tubes similar to amplifier 263 and to cathode ray tube 28L The motor 289 drives the rotating plate condenser 210, the static commutator such as 2', the'induction distributor 261, and any other necessa'ry member as described in the preceding embodiments. Condenser 210 is connected to receiver 212 and the output circuits that feed the carrier current emitter 268 may be actuated by any other member 218 that permits the obtaining of indications of a different kind. as described above. With an arrangement of this kind, it is accordingly possible to have as many indicating tubes as desired at different locations.

It must be understood that numerous modificationsand adaptations may be made in the different examples of embodiments shown and described without departing from the scope of the invention. both as regards the methods and the corresponding scanning circuits that are employed, as well as the groups of circuits that per mit the showing of the desired indications on the screen of a single cathode ray tube used as indicator. It must also be understood that the elements and circuits that are of well known design have not been described in detail since they do I claim:

1. A combined transmission supervision and direction finding system comprising a receiver, means to tune said receiver through a predetermined band of frequencies, an indicating device, means toproduce an indication 0 said device each time said receiver receives a signal from a transmitter,- means to separate the indications thus produced so as to identify the frequencies corresponding thereto, a direction finding antenna system associated with said receiver, means to change the directivity of said antenna system. and means to indicate on said indicating device a direction of any particular transmitter being received by said receiver. v 1

2. A combined transmission .supervision and direction finding system in accordance with claim 1, in which the indicating device is a cathode ray tube and the indication of each transmission appears as a luminous trace on the face of said tube. v

3. A combined transmission supervision and direction finding system in accordance with claim 1, in which the indicating device is a cathode ray tube upon which each transmission received appears as a luminous trace and in which means is provided for eliminating a Particular trace when the directivity of said direction finder antenna system bears a predetermined angular re lation to the direction of the transmitter at which said transmission originates.

4. A system in accordance with claim 1, in which means are provided for alternatively tuning said condenser automatically or manually.

5. A system in accordance with claim 1, in which one half cycle of the tuning of said receiver is rendered ineffective.

-6. A combined transmission supervision and direction finding system comprising a receiver, means to tune said receiver through a predetermined band' of frequencies, an indicating device. means to produce an indication on said device each time said receiver receives a signal from a transmitter, a direction finder antenna system associated with said receiver, means to change the directivity of said antenna system, means to indicate on said indicating device the direction' of a particular transmitter being received by said receiver, driving means rotated at a substantially constant speed. and manually operated means to alternatively connect said driving means to said receiver tuning means or to connect said manual means to said receiver tuning means for manual tuning of said receiver.

7. A system in accordance with claim 6, in which the indication means is a cathode ray tube.

8. A system in accordance with claim 6, in

which the indicator means is a cathode ray tube and in which means is provided to extinguish the luminous spot of said tube during a. half cycle of the tuning of the receiver.

9. A combined transmission supervision andcomprising a receiver,

direction finding system means to tune said receiver through a predetermined band of frequencies, an indicating device, means to control the indication of said device in one coordinate of a two coordinate system with the tuning of said receiver, means to control-the indication in the other coordinate by signals received by said receiver, direction finding apparatus associated with said receiver, means to adjust the directivity of said apparatus so that a particular signal received by'said receiver will be ma- Q in poles: cccrcinetes.

'10. iisystcin in accordance with claim 9, in

, which the meicciing device ice cetticde my cute directivity ci ceid eirecand means is provided to produce the indiceticn it of signals zeceivcdwith' seic, hand duringone heif cycle '05 the tuning oi cciii receiver, and means is proviiied during the other heii cvcie oi the tuning at said; receiver to produce an indifc'cticn on said tube of the 'crientetion at the ac directivity of said direction finding cpncrctus.

11, A system in accordance with claim 9, in

whicicthe indicating device is e. cathecie ray tubecnd in which the indication is nrceiucec thereon 12. A. combined transmission succi'visicn cud direction finding system cementing c. ccceivcr, meens tc time said receiver repeatedly thrcucyh s. predetermined band of frequencies, is cctiiccic my tube, means tc cause the spct cf seic', cctl-iciie, cc

mytube tctsece a circle in emciircnism with the tuning ci 5cm receiver, means tc csnsc seici spot tc deviate from said cix'cie when a. signal is received ity said receiver during one heir? cf the neecvcv I 17. A system in accordance withcieim 15, in

which the means to aitemete time coniomcter connections to the defiecticn' circuit of the cathode.

ray tube operates at e, cufficientiy high rate so that both indications will appear to an observer simui-' tcneousic on the face cf the tube.

18. A combined trensmissicn supervision and monitoring system comprising at central receiver,

means to tune said control receiver through a. predetermined bend of frequencies, are indicating device, meens tic-produce an indication en said cievice each time said receiver receives a signai from c. transmitter, means tc secerete this indications -thus m'cciuc'eci on said indicating device in c predcteimineoi manner so that the frequency of thesicnaisrccciveci may be i dentified, e. monitcr inc receiver, means to tune said receiver through said seine bend of frequencies, end means to produce on said indicating device an indication ccrrespcnding to the frequency at which said mcnitcrine receiver is tuned.

19. A system in ncccrdence with claim 18, in which the indicating devicc'is a, cathode ray tube. 2%]. A system in accordance with claim 18, in which the indie-sting device is a. cethccie my tube and the deflecting device comprises a coil rotct= 1 ably mounted cbcut the neck of sairltu'be end cycle of the tuning of ssici receiver, c direction $9 finding antenna. system, connected. tc scic re ceiver, means to eciiust the ditectivity ci said antenne system, means to'ceuse the spot 01' said cctiicde my tube to trace c. circular ncthixi said tube in-synchrcnism with the movement of the directivity of said antenna. system, during the other heii of the cycle of tuning oi. seiii i'eceiver and nieces tc-ccuse .seizi szecttc oscillate niece a cycle.

13. A system ineiccordence with claim 12, in

4 which the means to produce the indications from the output of the receiverv during one mu of the 5 radial line during said other half 02 the tuning 4 tuning cycle is en eiectronicccmmutetoz cper- 4 steci by the'tuning means. v

14. A system in accordance with claim 12, in which the deflection circuitfor. the ceti'icde ray 1 7 tube is connected alternatively to the output of the receiver and to the meansfci" controlling the movement 03 the spot during the ether hcii cycle o uni cf v v 15. A combined transmission supervision and direction finding system, comprising a. receiver,

means to tune said. receiver tnrougiie. predeter-- mined band of frequencies, is, cathode my tube,

' a, deflection circuit'for said cathode ray tube, ev first gonicmete: mechanicaiiy connected to said tuning meanejmcans to feed en eiterneting current intothe rater of said gonicmeter, means to said goniometer, a. direction finder antenna. system, means to adjust the directivity of said sys-, tem. a'seccnd gcniometer having its rotor meche'nicaiiy operated by said antenna ccjusting 0 said central receiver, a, seccnci gen its rotor mechanically ccnnectei'i t feed the output oi said receiver intc the rotor 02 5 current'tc the rctor of said first gcniometer, a cathode ray tu means is provided tc ccnnect said coil alternately to the output of the; ccntrci receiver emi' as the indicetionprcciucing means of the mcnitoring receiver.

21. A ccmbined tree cu cupervision and e centre? receiver,

means to tune said receivmined'bcnd of frequencies, a means to adjust the tuning c ceiver, a, first goniometcr chanicu'iiy ccnuected to tnc timing means for the monitoring receiver tively to connect the stators cf u\-' cters together, means in supply secc means to detect the output of tating deflecting c011, and means c connect said detecting means and is cutput of said ccntroi receiver to said deflecting mil.

22. A system in accordance with cieim in which means is providedto connect the output of said control receiver to said deflecting coil ciurinc one half only of the tuning cycle of said control receiver.

23. A combined transmission supervisien, directime finding, and monitoring system comprising an indicating device, a control receiver, means to tune said control receiver through a band of fre quencies a. monitoring receiver, means to adjust the tuning of said monitoring receiver, a d1recticn finder apparatus, means to produce an indication on said indicating device representing the means, means to feed an 'eitemeting current into'- the rotor oilscict gcnicmeter, means to feed the output of said receiver intc the rotor cf said. goniometei', and means to connect the stators of said first and second goniometcr' citez'netciy to said'deflecticn circuit.

.16. A system in accordance with cinim 15, in which the means to connect the'stctors oi the goniometei-s alternately with the deflection circuit of the. cathode ray tubeccmprises an electronic commutatcr.

signals received when said control receiver is tuned through said frequency band. with identification of the frequenciesof the signals received, means to produce an indication on said indicating device of the adjustment of said monitoring 0 receiver, means to produce an indication on said indicating device of the orientation of the dime-- tivity of said direction findingepperetus, and means sequentially to connect said three indication producing means to said indicating device.

24. A system inaccordance with claim 23, in which the indicating device is e cathode my tube.

I mum I 25. A system in accordance with claim 23, in UNITED B'I'A'IES- I{ A'I'EN'IB which the means for sequentially n ing the Number Name Date I indication producing means to the indicating de- I 1,878,787 Wallace Sept; 20, 1932 vice comprises an electronic commutator. 6 2,130,913 T0180 Sept. 20, 1988* i 2,21%,342 Neuieid -1. Sept. 10,1940 RENE HARDY- 2,233,914 i Wallace Feb. 24,1942 .v 2,2 9,151 Wallace Apr. 7, 1942 REFERENCES CITED 2,279,242: Poenak et a]; Apr. '1, 1942 The following references are oi record in the 2,381,956 Moseley Nov. 7, 1944 file of this patent: 7.90! Wallace Jan. 28, 1945 

